Pogonocaudina Sites and Zettel

Sites, Robert W. & Zettel, Herbert, 2011, Waterfall-inhabiting Naucoridae (Hemiptera: Heteroptera) of southern India and Sri Lanka: Pogonocaudina Sites and Zettel, n. gen., and a review of Diaphorocoris with descriptions of two new species, Zootaxa 2760, pp. 1-17 : 2-6

Pogonocaudina Sites and Zettel , NEW GENUS

Figs. 1–6

Type species: Pogonocaudina indica Sites and Zettel , NEW SPECIES

Description. Length 10.45–10.56 (mean = 10.50), maximum width 6.00–6.13 (mean = 6.06). Body elongate, parallel-sided, broadly rounded anteriorly and posteriorly, macropterous; widest across anterior half of embolia; dorsally head and pronotum light colored but heavily covered with brown punctures; scutellum and wings dark ( Fig. 1 ). Coarsely punctate throughout.

Head angled ventrad ca. 45o with respect to pronotum; compound eyes divergent, mesal and lateral margins slightly convergent anteriorly; lateral hyperoche widening anteriorly, anterior margin of eye subequal in length to head laterad of eye, black margin of head laterad and caudad of eye; series of four setal rosettes paralleling inner margin of eye; posterior margin of head slightly convex between eyes; apex of head deflexed, oriented posteriorly; broad, yellow, impunctate band along anterior margin immediately above deflexion; labrum broad, rounded; rostrum short, segment three (first visible anteriorly) partially concealed behind labrum, segment four narrower, reaching to near middle of prothoracic coxae; maxillary plates with brush of long hairs distally, hairs reaching apex of rostrum; antennae pale, segments one and two short and inconspicuous, three longest and gradually widened apically, four 3/4 length of three; antennae set behind brushes of long setae ventrally on head and proepimeron.

Pronotum concave behind eyes; dark punctation heavy throughout, dark pigmentation diminishing laterally; short, recumbent setae throughout, more evident laterally in absence of dark pigmentation; lateral margins smooth, convex; posterolateral corners broadly rounded; posterior margin straight to slightly convex; incomplete transverse sulcus setting off posterior one fourth more evident laterad of midline; transverse depression in anterior third. Propleura meeting prosternum; prosternal midline with wedge-shaped carina between coxae. Scutellum large, granulate, raised above level of wings, without paired protuberances, posterolateral margins sinuate. Mesosternum with broad tumescence and two rows of pegs at midline. Metaxyphus broadly triangular and slightly acuminate posteriorly. Forelegs with femur broad, strongly widened posterobasally; tibia narrow; tarsus single-segmented in both sexes ( Fig. 2 ); paired, articulated claws in both sexes ( Fig. 2 ). Middle and hind femora flattened, with anteroventral and posteroventral sparse rows of short spines; middle femur slightly curved dorsad; tibiae with numerous stout spines. Middle tibia gradually widening apically; male with dense pad of hairs beginning at middle of ventral surface and widening distally, pad reduced on female; single row of posteroventral heavy spines, multiple rows of anterior heavy spines, row of posterodorsal swimming hairs. Hind leg with tibia elongate, thin, multiple rows of spines on anterior and posterior margin, posterodorsal swimming hairs on tibia becoming more sparse on tarsi; tarsomere one short and produced beneath base of tarsomere two, two long, three longer. Mid- and hind pretarsi with empodia; claws symmetrical, long, evenly curved, each with basal tooth. Meso- and metathoracic coxae strongly recessed within thoracic venter; coxae with ventromesal series of stout hairs. Hemelytra and scutellum finely punctate with short setae, coarsely granulate. Hemelytra with distinct clavus and embolium; clavus with longitudinal suture between claval suture and scutellum, claval commisure with longitudinal ridge; embolium with proximal brush of long hairs; costal fracture at level of anterior 1/3 of abdominal segment IV; membrane evident by absence of punctation and coarse granulation. Hindwing with well-developed veins C, R, M, Cu, m-Cu, pCu, pCu- A, 1A, 2A; cells R, M; anal fold.

Abdomen dorsally dark brown; males with terga I–IV entire, V–VI dissociated into medio- and laterotergites, VII entire; all terga entire in females. Connexival margin II smooth, III–IV set with stout peg-like setae, posterior ¼ of IV and entire length of V–VIII with extremely long, dense fringe of brown hairs in both sexes ( Fig. 3 ). Abdomen ventrally generally covered with fine, light colored setae; with glabrous yellowish lateral band; strong brush of midventral brown hairs beginning on III, widening and continuing to posterior end of abdomen. Spiracle on II at anterior margin, concealed beneath metepimeron; spiracles III–VI evident between and slightly anterior to paired glabrous patches.

Diagnosis. The most striking unique attribute of this insect is the dense fringe of long hairs around the perimeter of the posterior abdominal segments in both sexes ( Fig. 3 ). This genus can be recognized further by the male forelegs having one tarsal segment, which is similar to the condition of Namtokocoris , but with two pretarsal claws ( Fig. 2 ) as in males of all other known Laccocorinae . The scutellum is elevated slightly above the level of the hemelytra as in Namtokocoris and Diaphorocoris . However, unlike Namtokocoris and Diaphorocoris , linear series of stout hairs on the hemelytra and scutellar protuberances are lacking. Other subfamily attributes of Laccocorinae are present, including a sexually dimorphic pad of hairs on the mesotibia, a dense midventral abdominal band of hairs, the front of the head folded posteroventrally, and a well-developed labrum.

Discussion. The front tarsal condition differs among the genera of Asian Laccocorinae : Although most genera are sexually dimorphic, where the male has two tarsal segments and the female one, both sexes of Ctenipocoris have two segments and both sexes of Namtokocoris have one segment. Thus, Pogonocaudina is similar to Namtokocoris in the possession of single-segmented front tarsi in both sexes but differs in having paired pretarsal claws, among other features: a straight posterior margin of the pronotum instead of convex; no scutellar protuberances; mesotibia with a row of posterodorsal swimming hairs instead of a dorsal row of spines; the legs are proportionately longer and less spinose; the dense midventral band of hairs begins on III instead of V; the lack of a long row of erect hairs setting off the glabrous ventral lateral abdominal band; the female has mediosternite VI transverse instead of triangular and narrowly pointed; and the digitate lobe of laterosternite V is unique.

The secondary longitudinal suture within the clavus was observed in all specimens examined, and appears to correspond with macroptery. All specimens examined for hindwing condition were macropterous.

Based on the character states in common with other members of the subfamily, Pogonocaudina clearly appears to be most closely related to Namtokocoris and Diaphorocoris . The latter genera previously were considered to be closely related (Sites & Vitheepradit 2007), and Pogonocaudina has features in common with each of them, and elevation of the scutellum and waterfall habitation with both of them ( Table 1 ). All three of these genera have a dense midventral hair band in common with Ctenipocoris. Analysis including molecular data is needed to more effectively evaluate phylogenetic relationships.

Ecological notes. Specimens of Pogonocaudina were observed on smooth surfaces of a granite waterfall at the type locality ( Fig. 4 ), usually associated with a film of water and in contact with fallen leaves ( Figs. 5 , 6 ) or at least on wet rock surfaces and algae. Some individuals were associated with small organic debris dams comprising sticks and leaves, where water trickled through but most water was held back in small pools; thus, some current was present at this microsite. Other insects were present on the rock surfaces of the waterfall, including mayflies, hydrophilids (including Scoliopsis ), gerrids, and the naucorid Diaphorocoris . Detailed accounts of waterfall-inhabiting insects in Thailand and elsewhere in Indochina were given for Oocyclus (Hydrophilidae) by Short & Swanson (2005), Eotrechus (Gerridae) by Vitheepradit & Sites (2007), and Namtokocoris (Naucoridae) by Sites & Vitheepradit (2007).

The discovery of Pogonocaudina adds to a growing number of naucorid genera known to occur exclusively or facultatively in waterfalls. In Indochina, Namtokocoris is restricted to waterfalls, although individuals occasionally drift downstream (Sites & Vitheepradit 2007). Many nymphs of Cheirochela have been collected on waterfalls in Thailand and Vietnam, although adults have been collected on large rocks in fast current (Sites & Vitheepradit 2007). In India, Diaphorocoris was found on wet rock surfaces of waterfalls, including with Pogonocaudina at its type locality. From Mexico to Central America in the New World, Cataractocoris can be found in waterfall habitats, including in sheeting water on vertical rock surfaces, the waterfall splash zone, and fast current in turbulent, rocky streams ( Sites 2004).

Etymology. This genus is named for the dense fringe of long hairs around the perimeter of the posterior abdominal segments. "Pogono-" is Greek for beard, and "caud-" is Latin for tail or posterior end.

Material examined. See species localities.

Figures

FIGURE 6. Live specimen of Pogonocaudina indica n. sp.

FIGURES 1 – 3. Features of Pogonocaudina, n. gen.: (1) habitus (dry specimen), (2) single segmented front tarsus with paired claws of male appressed to anterior margin of femur, (3) dense fringe of long setae on outer margin of posterior abdominal segments (specimen in alcohol).

FIGURES 4 – 5. (4) Kiliyur Waterfall, the type locality of Pogonocaudina indica n. sp. and Diaphorocoris kiliyur n. sp., (5) habitat of Pogonocaudina indica n. sp., Diaphorocoris arunachalami n. sp. and Diaphorocoris kiliyur n. sp.

Tables

TABLE 1. Character comparison of Pogonocaudina with other Asian genera of Laccocorinae.

Character	Namtokocoris	Pogonocaudina	Diaphorocoris Ctenipocoris	Laccocoris	Heleocoris
dense caudal fringe of hairs	no	yes	no no	no	no
male protarsal segments	1	1	2 2	2	2
pretarsal claws on foreleg	1	2	2 2	2	2
expansive, thin, prosternal carina	yes	no	no no	no	no
scutellar protuberances	distinct	no	weak no	no	no
scutellum elevated	yes	yes	yes no	no	no
hair lines on hemelytra	yes	no	yes no	no	no
dense midventral band of hairs	yes	yes	yes yes	no	no
on abdominal sterna V–VII/VIII
dimorphic pad of hairs on mesotibia	yes	yes	yes yes	yes	yes
front of head folded posteroven- trally	yes	yes	yes yes	yes	yes
well-developed labrum	yes	yes	yes yes	yes	yes